In the past 20 years biomedical research has experienced an explosion in the technologies that facilitate manipulation of the mouse genome. These technologies are readily accessible to most investigators, and as a result, a tremendous number of valuable induced mutant mouse strains are being continuously generated. Given the high cost to individual laboratories for the maintenance and distribution of such strains, it is essential that we develop high efficiency expert resource centers to import, characterize and distribute mutant mice. Such facilities should maintain high standards in the maintenance and propagation of strains, advance our understanding of the most broadly useful strains, and develop technologies that facilitate the efficient generation and phenotypic analysis of such strains. UNC has had a long standing commitment to the use of the mouse in biomedical research, as evidenced by the large number of prominent UNC investigators committed to this approach. UNC maintains state of the art housing and support facilities for large numbers of pathogen-free mice, along with core research facilities that enable mouse model studies. These include the Animal Models, Histopathology, Clinical Chemistry, and RIA cores. Exceptional personnel staff these resources at all levels. Specific aims of the UNC-MMRRC are to: (1) Import, rederive, genotype, maintain and distribute new mouse strains. In the first year, 15 new strains will be imported, growing to 30 new strains per year in subsequent years; (2) Cryopreserve new and existing mutant strains; (3) Interface with the IMR and other MMRRC nodes in the acquisition, storage, and exchange of data and the development of technologies; (4) Phenotypically characterize a specified number of mouse strains with regard to histopathological, physiological, cell biological and molecular abnormalities. Special expertise at UNC for possible extensive analyses exists in the fields of Cancer, Cardiovascular Biology, Immunology, and Neuroscience; (5) Develop the ability to efficiently "clone" mice from somatic cells. In the UNC Animal Models Core, Dr. Thresher will expand current efforts by the Dr. Oliver Smithies' lab; (6) Develop "reporter" mouse strains that will facilitate rapid phenotyping within particular cell/tissue types. As a test system for the feasibility of developing/providing such strains alone or induced mutant backgrounds, a limited number of strains that express green fluorescent protein (GFP) in specific cell types will be obtained or generated and studied.